if the t_order table and t_order_item table are both sharded according to order_id and are correlated using order_id, the two tables are binding tables. The multi‐table associated queries between binding t_order_item i ON o.order_id=i.order_id WHERE o. order_id in (10, 11); In the case where no binding table relationships are being set, assume that the sharding key order_id routes the value 10 to slice JOIN t_order_item_0 i ON o.order_id=i.order_id WHERE o. order_id in (10, 11); SELECT i.* FROM t_order_0 o JOIN t_order_item_1 i ON o.order_id=i.order_id WHERE o. order_id in (10, 11); SELECT i.* FROM

if the t_order table and t_order_item table are both sharded according to order_id and are correlated using order_id, the two tables are binding tables. The multi‐table associated queries between binding t_order_item i ON o.order_id=i.order_id WHERE o. order_id in (10, 11); In the case where no binding table relationships are being set, assume that the sharding key order_id routes the value 10 to slice JOIN t_order_item_0 i ON o.order_id=i.order_id WHERE o. order_id in (10, 11); SELECT i.* FROM t_order_0 o JOIN t_order_item_1 i ON o.order_id=i.order_id WHERE o. order_id in (10, 11); SELECT i.* FROM

if the t_order table and t_order_item table are both sharded according to order_id and are correlated using order_id, the two tables are binding tables. The multi‐table associated queries between binding t_order_item i ON o.order_id=i.order_id WHERE o. order_id in (10, 11); In the case where no binding table relationships are being set, assume that the sharding key order_id routes the value 10 to slice JOIN t_order_item_0 i ON o.order_id=i.order_id WHERE o. order_id in (10, 11); SELECT i.* FROM t_order_0 o JOIN t_order_item_1 i ON o.order_id=i.order_id WHERE o. order_id in (10, 11); SELECT i.* FROM

if the t_order table and t_order_item table are both sharded according to order_id and are correlated using order_id, the two tables are binding tables. The multi‐table associated queries between binding t_order_item i ON o.order_id=i.order_id WHERE o. order_id in (10, 11); In the case where no binding table relationships are being set, assume that the sharding key order_id routes the value 10 to slice JOIN t_order_item_0 i ON o.order_id=i.order_id WHERE o. order_id in (10, 11); SELECT i.* FROM t_order_0 o JOIN t_order_item_1 i ON o.order_id=i.order_id WHERE o. order_id in (10, 11); SELECT i.* FROM

table with the same sharding rules, for example, t_order and t_order_item are both sharded by order_id, so they are binding tables with each other. Carte‐ sian product correlation will not appear in the t_order o JOIN t_order_item i ON o.order_id=i.order_id WHERE o. order_id in (10, 11); When binding table relations are not configured, suppose the sharding key order_id routes value 10 to sharding 0 and value JOIN t_order_item_0 i ON o.order_id=i.order_id WHERE o. order_id in (10, 11); SELECT i.* FROM t_order_0 o JOIN t_order_item_1 i ON o.order_id=i.order_id WHERE o. order_id in (10, 11); SELECT i.* FROM

affect query efficiency. For example, t_order and t_order_item are both sharded by order_id, and use order_id to correlate, so they are binding tables with each other. Cartesian product correlation will t_order o JOIN t_order_item i ON o.order_id=i.order_id WHERE o. order_id in (10, 11); When binding table relations are not configured, suppose the sharding key order_id routes value 10 to sharding 0 and value JOIN t_order_item_0 i ON o.order_id=i.order_id WHERE o. order_id in (10, 11); SELECT i.* FROM t_order_0 o JOIN t_order_item_1 i ON o.order_id=i.order_id WHERE o. order_id in (10, 11); SELECT i.* FROM

affect query efficiency. For example, t_order and t_order_item are both sharded by order_id, and use order_id to correlate, so they are binding tables with each other. Cartesian product correlation will t_order o JOIN t_order_item i ON o.order_id=i.order_id WHERE o. order_id in (10, 11); When binding table relations are not configured, suppose the sharding key order_id routes value 10 to sharding 0 and value JOIN t_order_item_0 i ON o.order_id=i.order_id WHERE o. order_id in (10, 11); SELECT i.* FROM t_order_0 o JOIN t_order_item_1 i ON o.order_id=i.order_id WHERE o. order_id in (10, 11); SELECT i.* FROM

t_order_item 表，均按照 order_id 分片，则 此两张表互为绑定表关系。绑定表之间的多表关联查询不会出现笛卡尔积关联，关联查询效率将大大提 升。举例说明，如果 SQL 为： SELECT i.* FROM t_order o JOIN t_order_item i ON o.order_id=i.order_id WHERE o. order_id in (10, 11); 3.1. 在不配置绑定表关系时，假设分片键 order_id 将数值 10 路由至第 0 片，将数值 11 路由至第 1 片，那 么路由后的 SQL 应该为 4 条，它们呈现为笛卡尔积： SELECT i.* FROM t_order_0 o JOIN t_order_item_0 i ON o.order_id=i.order_id WHERE o. order_id in (10, 11); SELECT JOIN t_order_item_1 i ON o.order_id=i.order_id WHERE o. order_id in (10, 11); SELECT i.* FROM t_order_1 o JOIN t_order_item_0 i ON o.order_id=i.order_id WHERE o. order_id in (10, 11); SELECT i.* FROM

table with the same sharding rules. for example, t_order and t_order_item are both sharded by order_id, so they are binding tables with each other. Carte‐ sian product correlation will not appear in the t_order o JOIN t_order_item i ON o.order_id=i.order_id WHERE o. order_id in (10, 11); When binding table relations are not configured, suppose the sharding key order_id routes value 10 to sharding 0 and value ON o.order_id=i.order_id WHERE o. order_id in (10, 11); 4.2. Sharding 24 Apache ShardingSphere document, v5.0.0 SELECT i.* FROM t_order_0 o JOIN t_order_item_1 i ON o.order_id=i.order_id WHERE o. order_id

org/dtd/mybatis-3-config.dtd"> id="development"> id="selectBlog" resultType="Blog"> select * from Blog where id = #{id} 对于这个简单的例子来说似乎有点小题大做了，但实际上它是非常轻量级的。在一个 mybatis.example; public interface BlogMapper { @Select("SELECT * FROM blog WHERE id = #{id}") Blog selectBlog(int id); } 对于简单语句来说，注解使代码显得更加简洁，然而 Java 注解对于稍微复杂的语句就会力不从心并且会显得更加混乱。因此，如果你 需要做很复杂的事情，那么最好使用